All right, they suckered me. I thought that What?! were starting a gimmick tradition of rolling out cute singles named after foodstuffs. A natural suspicion – their debut single had the crowd-pleasing title of Tikka Masala. Actually, it turns out that “schwaffelen” is Dutch slang, and refers to a man repeatedly bouncing his semi-erect penis off assorted objects (ranging from someone else’s cheekbone to the side of the Taj Mahal). Handy phrase – consider me educated. I’ve been saved some embarrassment the next time I’m snacking in Amsterdam, but have been left with a delightful image of waffles-and-cream that I now need to bleach from my mind. Thanks for that.

What?! remain the kind of supple instrumental trio that gives slick a good name – guitar, bass guitar, drums and a thorough versing in everything out there which grooves. They also own a not-so-secret knowledge of plenty of things which don’t groove but which do lurk, puzzle over things and then jump out at you. But they’ve yet to really show their other teeth: those rougher, odder inspirations they claim to get from Zappa, Dub Trio and Mr Bungle. So far, they’ve been more about delicate sunlit jazzy chords and walks, clean deft swing, and plenty of space. You get the feeling that they could do anything with their material – as soon as they wanted to – and that they’re fencing with expectations. It’s just that it’s still not clear when they’re going to stop fencing and start carving.

As much as you might want them to get nastier, Schwaffelen doesn’t show What?! chucking away any of their finesse in favour of skronk or sludge. If they’re stepping towards a spikier direction, they’re starting subtle – taking some sour art-rock patterns and passing them back and forth through the smooth-jazz filter. As with Tikka Masala, there’s a hint of Take 5 in the gently precise stops and feints as a bossa nova is displaced and reshuffled into math-rock spikes. But the truth is that, in spite of the cock-bouncing title, What?! keep their all-things-to-all-men decorum throughout – even when hitting the distortion pedals.

If you’re hoping for some upheaval – something like the obsessive rhythmic knotting of Battles, say, or the disruptive slice-and-dice of Naked City – you’re in the wrong place. Schwaffelen’s flexing sections do include a flawless switch into driving rock as guitarist Niels Bakx starts blasting away and Agostino Collura’s nimble bass drops its funky slither and locks down into root-note pummeling. But this is more an exercise in clever distraction. Even as Raphael Lanthaler drums along at motorway-punk velocity, the whole band are keeping an eye on the little loping twists of the original rhythm: as it ghosts on underneath, they’ll lock seamlessly back into it whenever they choose. Even the texture phase (in which Niels seems to be channeling the sparse echo-spangled touch of Andy Summers) adds some extra breadth but no questioning depth or disruption.

Perhaps it doesn’t matter – whatever else they might or might not do, What?! remain supremely elegant puzzlers. But it still feels as if there’s much more to them. The Key Ness remix of Schwaffelen is barely half the length of the original, but during its stay it chops, rewinds and pans the original riffs around a gastric roller-coaster of sub-bass and boiling P-Funk synth. Along the way, it twirls past Alice Coltrane harp cascades, brief bursts of classical soul orchestras, wind-tossed shouts from hip-hop MCs and gutsy flowerings of Spanish guitar. It sounds more like what must go on in the trio’s heads – what they must listen to on iPods, gulp down from session to session, or coast by on the bus.

One last thing, going back to the original track… As it snaps to a halt and telescopes away, with a quick twist-and-growl, those push-pulling rhythms leave you in a state of expectation. There’s a moment of hover. Then there’s several messy, prolonged seconds of the most horrendous splurging musical spoff-noise you can imagine. Maybe it’s a surprise, a pancaked blast-beat hurled out by Raphael to be crushed flat in the mix. Whatever it is, it’s a Zappa-style kiss-off. Perhaps I’ve been unfair to What?!. They did finally deliver that dirty splatter.

Sometimes you can come across simple treasures hiding in the backroom. Dutch guitarist Niels Bakx, Sicilian drummer Raphael Lanthaler and Tyrolean bass player Agostino Collura are part of that under-appreciated swirl of humble, talented international musicians who fly in, settle down and quietly underpin bands in London, as in many big cities. People like these plug away behind the people with the big ideas and the knack for fronting. They’re the ones who finesse the roughness, who add the musical depth and the polish which brings shine and sophistication to performance. And sometimes, they secretly bring more.

Individually, each of these three have clearly got the chops and the temperament to keep themselves in demand with songwriters (Agostino plays with Anna Waldmann’s band The Cry Baby, Niels and Raphael back Charlotte Eriksson in The Glass Child), embedded in soul collectives (Agostino’s work with Retrospective For Love) and driving mixed groove-band (Raphael’s Snail Trail). Together, though, Niels, Raphael and Agostino are something else.

As What?!, they’re an assured and formidable unit; an airy, confident groove-trio audibly revelling in their flexibility and their knack for carefully-sprung timing. On spec, there’s nothing particularly unusual in what they do. Enough years spent plugging away at sessions and keeping punters happy with funk, soul, jazz and reggae tunes have made them experts in warm, sunny, foot-moving musicality: but it’s what’s beyond the blueprint that’s interesting.

Their debut single Tikka Masala (named, consciously or not, after a meal made up on the spot to keep British customers happy) is a sweet-natured hall-of-mirrors groove, light and slinky. There’s reggae in it, thanks to Raphael’s displaced bass drum taps, his tight-tuned tom rattles and Niel’s skinny-supple rhythm guitar. There’s funk in the warm spaces between strokes and beats. There’s jazz in everything, from the little golden runs of licks to the turnarounds to the feel that the rhythms are to be flung from hand to hand, danced over, teased and tag-teamed around. There are subtle refractions, interruptions of rhythm and key, that make you think briefly of progressive rock at its least bombastic and most aware. There are also flares of hard rock when all three musicians line up under a suddenly roaring guitar and suddenly start jabbing together ahead of the beat.

What’s really special about it is their complete control over the music. Their discipline is absolute but relaxed, with the feel that at any time they could shift rhythm, speed, genre back and forth in a moment, and yet not drop a single thing along the way. There are no self-conscious cut-ups in What?!’s music – no need to deconstruct. Why should there be when they’re masters of structure? – so much that if you flipped Tikka Masala around and spun it backwards it would keep every bit of its symmetry and bounce. For a demonstration of this, play the bonus track Alasam Akkit as that’s exactly what that is – a backwards-play of the A-side which sounds almost as good as the forwards version. A backwards-play which you can still dance to. Remarkable.

Exactly what this leads to, I’m not sure. Perhaps the outcome is that What?! set themselves up as a twenty-first century Sly and Robbie-plus-one. Perhaps they remain a supremely-accomplished hobby band, something which the trio engage in when they’re not otherwise employed keeping other people happy. Or do they push ahead as self-sufficient instrumentalists, seeing how far they can push, stretch and double-feint their masterful musicality? The only thing I can be sure of is that, whenever they do get together, all ways – for those moments – are open; and it’s tremendously refreshing.